Number of K_s sources per magnitude in bins of 0.5 mag (dashed line) compared with (full line): the number of K_s sources with also good detections both at J and Ha), northern field; f) southern field; the number of K_s sources with also good detections either at both J and H or at least at H, and in the IRAC 4.5 μm band b), northern field; g) southern field; the number of K_s sources with also good detections in all four IRAC bands c), northern field; h) southern field; the number of K_s sources with also good detections in the first three IRAC bands d), northern field; i) southern field; the number of K_s sources that exhibits an X-ray emission e), northern field; j) southern field. We only took into account sources with photometric uncertainty <0.3 mag in all the considered bands. In addition, the samples plotted in panels c), d), h), i), have been rid of sources with colours indicating PAH contamination as explained in Appendix D. On the upper left corner of each box, a xN tag indicates whether the histograms plotted have been multiplied by a constant N to expand the scale. The vertical dotted lines mark the K_s values at which ~80% of the K_s sources are still retrieved when requiring simultaneous valid detections in other bands.